Systems and methods herein generally relate to machines having print engines such as printers and/or copier devices and, more particularly, to color management in image/text printing.
Conventional digital reprographic systems receive electronic image(s), which are passed to an image-processing unit. The image-processing unit may be a combination of software and hardware elements that accepts the electronic images from different sources and performs operations needed to convert the images to the format compatible with the output path of the digital reprographic system.
For example, a conventional image-processing unit may convert continuous tone image data into binary image data. The conventional image-processing unit may convert the binary image data into a reduced coverage (economy mode or draft mode) bitmap of binary image data. Conventional digital reprographic systems convert image data into a reduced coverage (economy mode or draft mode) bitmap of binary image data to save toner or ink usage. The economy mode may have the same resolution as a regular print mode in a conventional digital reprographic system, but a color table or a transfer function reduces toner or ink usage.
In general, maximizing the toner yield on an electro-photographic printer is achieved by reducing the usage of toner in printers, especially in color printers. When printing in an economy mode, a data stream representing the image may be processed so that the printer uses less marking material (ink or toner) to print the image than it would if the processing was not performed. Several methods are currently in use but there are trade-offs with respect to image quality.
The current toner savings methods can be broadly classified into the following categories:                1. Reducing halftone frequency—By default, using low frequency halftone will result in higher toner yields/cartridge or bottle. It is easier to implement and no additional processing time is required. It will directly lead to high toner savings at the cost of image quality.        2. Adjusting tone reproduction curve (TRC)—This method is very simple and easy to implement. The toner consumption can be reduced with a simple adjustment to the TRC. TRC may be applied on the halftone threshold array and the resultant threshold array can be applied on the input image to render it. Adjusting the TRC is very simple to implement and the processing time is about the same as the time for applying TRC on halftone. This TRC method will provide high toner saving with a trade-off on quality.        3. Using neighborhood processing—In this method, a rendered image (halftoned plane) is used to decide which pixel needs to be turned on/off. This method will provide moderate toner saver with acceptable image quality; however, it is more complex to implement. This method requires additional processing time for a transfer function that determines which pixels are needed to be marked on paper (e.g., removing center pixel from a 3×3 array).        4. Optimizing print engine and IOT components for better toner yields.        
All of the above mentioned methods have significant impact on the image quality. Some of these methods achieve savings by trading the quality of output. In one of the methods (Controlling Colors by TRC) the colors may be washed away, other methods create artifacts in the image; and some methods are suitable only for Black and White.
Additionally, for color printers, each color toner is used at a different rate. Generally, when a printer is low on one toner, the printer device warns the user to replace that particular toner. When the toner level reaches a critical point, the user is unable to print any document until the empty toner is replaced.